1. Field of the Invention
Aspects of the present invention relate to a secondary battery, and more particularly, to a secondary battery that can exactly connect a protection circuit board to a predetermined position of the battery.
2. Description of the Related Art
Compact and light-weighted portable electronic devices, such as a cellular phone, a notebook computer and a camcorder, etc., have been actively developed and produced. Such portable electronic devices include a built-in battery pack so as to be operable without a separate power supply. The battery pack is equipped with a secondary battery that can be charged/discharged. Typical secondary batteries are a nickel-cadmium (Ni—Cd) battery, a nickel-hydrogen (Ni-MH) battery, a lithium (Li) battery, and a lithium ion (Li-ion) secondary battery, etc. Especially, the lithium ion secondary battery has an operating voltage that is three times that of the nickel-cadmium (Ni—Cd) battery or the nickel-hydrogen(Ni-MH) battery, which are usually used as power supplies for the portable electronic devices. In addition, the lithium ion secondary battery has been widely used because the lithium ion secondary battery has higher energy density per unit weight.
The lithium ion secondary battery uses a lithium group oxide as a cathode active material, and a carbonic material as an anode active material. Generally, secondary batteries are divided into a liquid electrolyte battery and a polymer electrolyte battery, depending on a kind of an electrolyte. A lithium ion battery uses a liquid electrolyte, and a lithium polymer battery uses a polymer electrolyte.
The secondary battery controls matters about charge/discharge when it is charged or discharged. A protection circuit board is electrically and mechanically combined with the secondary battery so as to disconnect current flow of the charge/discharge in cases of overheating and overcurrent. For example, the protection circuit board is electrically and mechanically combined with a cap plate of the secondary battery.
In the conventional secondary battery, there is a problem that the position of the protection circuit board is easily changed during a combining process as the protection circuit board is simply placed on the flat cap plate and combined therewith. That is, the protection circuit board seated on the flat cap plate easily becomes loose by assembling errors or small external impacts. Thus, positions of the protection circuit boards between completed secondary batteries are somewhat different from each other. Sometimes, the position of the protection circuit board is too much changed such that the completed secondary battery cannot be mounted in an electronic device.